Continuous layer-multiplying coextrusion processing of metal-filled polymers into conducting structures has been described in “Polymer microlayer structures with anisotropic conductivity,” S. Nazarenko, A. Hiltner and E. Baer, Department of Macromolecular Science, and Center for Applied Polymer Research, Case Western Reserve University, Cleveland, Ohio 44106-7202, Journal of Materials Science, 34 (1999) 1461-1470 (Kluwer Academic Publishers), the disclosure of which is incorporated herein by reference in its entirety. In this process, filled and unfilled polymers are combined into unique structures with many alternating layers of two or more components. The total number of layers can range from tens to thousands. The ability of microlayering to “organize” anisotropic particles was used to obtain metal-filled polypropylene tape with highly anisotropic electrical properties. Orientation of metal flakes by microlayering increased the anisotropy in resistivity by two orders of magnitude over compression molding. Isolation of individual filled layers by alternating filled and unfilled layers resulted in materials with many independent conducting pathways. Filled layers with 10% (v/v) copper flakes or 15% (v/v) nickel flakes were conductive only if the filled layers were thick compared to the thickness of the flake particles. When the thickness of the filled layers approached the particle thickness, the conductive properties were lost. This behavior was understood by comparing the three-dimensional arrangement of flakes in thick conductive layers with the two-dimensional particle layout of thin non-conductive layers.
General principles regarding the methods and extrusion dies that can be adapted to form the microlayer electrical conducting extrusions in products layer by layer as well as dies in which the layers are created through folding may be found in U.S. Patent Publication No. 2012/0189789 “Method and Apparatus for Forming High Strength Products” and in U.S. Pat. No. 7,690,908 issued Apr. 6, 2010 referring to folded flows with nanofeatures. Other methods are described in U.S. Pat. Nos. 6,669,458, 6,533,565 and 6,945,764. Each of the aforesaid publication or patent is herein incorporated by reference in its entirety.
In one specific microlayer extrusion process, each of the laminated flow streams is subject to repeated steps in which the flows are divided and overlapped to amplify the number of laminations. The amplified laminated flows are rejoined to form a cumulated laminated output which can achieve dimensions as thin as the micro or nanometer range. One example of a device that can be used in a microlayer extrusion process to create a laminated output is US Patent Publication 2012/0189789, filed on Dec. 23, 2011, entitled Method and Apparatus for Forming High Strength Products, the disclosure of which is incorporated herein by reference in its entirety. This nano-flow die device (referred to herein as the “nano-flow die”) can be used to create layers in a multi-layered product that have at least one dimension in the nanometer range.